const fp = require('lodash/fp');

const cars = [
    {
        name: 'Ferrari FF', horsepower: 660, dollar_value: 700000, in_stock: true
    },
    {
        name: 'Spyker C12 Zagato', horsepower: 650, dollar_value: 648000, in_stock: false
    },
    {
        name: 'Jaguar XKR-S', horsepower: 550, dollar_value: 132000, in_stock: false
    },
    {
        name: 'Audi R8', horsepower: 525, dollar_value: 114200, in_stock: false
    },
    {
        name: 'Aston Martin One-77', horsepower: 750, dollar_value: 1850000, in_stock: true
    },
    {
        name: 'Pagani Huayra', horsepower: 700, dollar_value: 1300000, in_stock: false
    }
]

//1. fp.flowRight

let isLastInStock = fp.flowRight(fp.prop('in_stock'), fp.last);
console.log(isLastInStock(cars));

//2. get first name;

let getNameOfFirst = fp.flowRight(fp.prop('name'), fp.first)
console.log(getNameOfFirst(cars))

//3. 重构averageDollarValue

let _average = function (xs) {
    return fp.reduce(fp.add, 0, xs)/xs.length;
}

// let averageDollarValue = function (cars) {
//     let dollar_value = fp.map(function(car){
//         return car.dollar_value;
//     },cars)
//     return _average(dollar_value)
// }

let averageDollarValue = fp.flowRight(_average, fp.map(car=>car.dollar_value) )
console.log(averageDollarValue(cars));

//4. 

let _underscore = fp.replace(/\W+/g, '_');
let sanitizeNames = fp.flowRight(_underscore, fp.toLower, fp.map(car=>car.name))
console.log(sanitizeNames(cars))
